Packaging – When is 8 ounces not 8 ounces?
When selecting cosmetic packaging it is necessary to consider that advertised sizing is only a rough approximation of the quantity of product that will fit in the packaging. An eight-ounce bottle, for example, is described as “8 oz.” because it will fit 8 oz. of water. Cosmetic products, including lotions, crèmes, facial cleansers, serums, scrubs, etc. may vary substantially in density. A bottle that fits 8 oz. of water may not fit 8 oz. of a crème and a bottle that fits 8 oz. of one crème may not fit 8 oz. of another crème. The packaging manufacturer has to provide some indicator of approximately how much product is likely to fit, but a so-called 8 oz. bottle is not guaranteed to fit 8 oz. of anything whatsoever and it may not fit 8 oz. of your product in particular.
The same applies to other types of packaging. An eight-ounce tube, for example, is described as “8 oz.” because it will fit 8 oz. of water prior to being sealed. The sealing process pinches the end of the tube thereby reducing the quantity of product the tube can hold. Tubes vary in thickness and mechanized tube sealers vary in their precise specifications. One sealer might pinch off 0.12” of the tube and another sealer might pinch off 0.25”. A so-called “8 oz.” tube will fit 8 oz of water prior to being sealed, but may only fit 7.5 oz. of water or 6.75 oz. of lotion or 6.5 oz. a crème after being sealed. The tube manufacturer can’t know the density of the product you intend to package in the tube and they can’t know exactly how much space will be lost when the tube is sealed.
For these reasons, it is critical to establish the fill volume or weight of a product before creating labels. We know that fill volume can be confusing, so another way to think about it is by fill weight. The classic example of 1 ton of feathers versus 1 ton of bricks may apply here. If you were to weigh 10 pounds of bricks out on a scale and then weigh 10 pounds of feathers out on a scale. You would have many more feathers than bricks. While the bricks and feathers are the same weight, the bricks have less volume.